Acute mesenteric ischemia is a rare but severe complication after open heart surgery. Its incidence is quite low, but the mortality rate is reported to be tremendously high. This study reported a 63-year-old male who underwent coronary artery bypass grafting due to three-vessel coronary artery disease and non-ST segment elevation myocardial infarction. The operation of coronary artery bypass grafting was performed smoothly without immediate complication. On postoperative day 2, acute abdominal pain developed and acute mesenteric ischemia was considered via physical examination and computerized tomographic scan. An exploratory laparotomy revealed segmental necrosis of jejunum and bowel resection followed by end-to-end anastomosis was performed. This patient had an uneventful recovery and was discharged under a good functional status.